Extracting data from different sheets / tabs etc to a common matrix

Hi All,

I get sent user data from different system administrators. that I need to collate for checking

Each System has multiple users and a user may have access to multiple systems.

In the example spreadsheet, I have labeled each tab by system. What I want to achieve is extracting the data from each of the systems, identifying and listing all the unique users in column A on the "User to System Matrix", Using the Tab name to identifying the systems in Row 1 (this may change and will not be consistent).

I then want to identify in the matrix what systems a user has access to (left to right), or what users are listed in a system (top to bottom) and concatenate all the systems a user has access to at the end.

I'm not worried about additional control sheets or columns which may or may not be hidden as long as I can come up with something resembling the "User the System Matrix" Tab at the end.

I'm quite happy with Macros, formula etc. But honestly, right now I haven't a clue where to start.

Any help would be gratefully appreciated.

Kindest Regards

Magic Man